Chimeric phage-bacterial enzymes: a clue to the modular evolution of genes.

abstract：:The rate of change of climate codetermines the global warming impacts on natural and socioeconomic systems and their capabilities to adapt. Establishing past rates of climate change from temperature proxy data remains difficult given their limited spatiotemporal resolution. In contrast, past greenhouse gas radiative f...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Joos F,Spahni R

更新日期：2008-02-05 00:00:00

abstract：:Sleep is recognized as a physiological state associated with learning, with studies showing that knowledge acquisition improves with naps. Little work has examined sleep-dependent learning in people with developmental disorders, for whom sleep quality is often impaired. We examined the effect of natural, in-home naps ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Spanò G,Gómez RL,Demara BI,Alt M,Cowen SL,Edgin JO

更新日期：2018-11-13 00:00:00

abstract：:A recently determined set of 20 NMR-derived conformations of a 48-residue all-alpha-helical protein, (PDB ID code 2JVD), is validated here by comparing the observed (13)C(alpha) chemical shifts with those computed at the density functional level of theory. In addition, a recently introduced physics-based method, aimed...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Vila JA,Aramini JM,Rossi P,Kuzin A,Su M,Seetharaman J,Xiao R,Tong L,Montelione GT,Scheraga HA

更新日期：2008-09-23 00:00:00

abstract：:The Japanese firefly squid, Watasenia scintillans, emits intense flashes of light from three tiny luminous organs that are located at the tip of each of a pair of ventral arms. Light is also produced from hundreds of other minute organs that are scattered over the body. The luminescence is due to an ATP-dependent reac...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Tsuji FI

更新日期：1985-07-01 00:00:00

abstract：:Calcium sensitivity of myosin cross-bridge activation in striated muscles commonly varies during ontogeny and in response to alterations in muscle usage, but the consequences for whole-organism physiology are not well known. Here we show that the relative abundances of alternatively spliced transcripts of the calcium ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Marden JH,Fitzhugh GH,Wolf MR,Arnold KD,Rowan B

更新日期：1999-12-21 00:00:00

abstract：:We utilized the presence of hepatic receptors for galactose-terminal glycoproteins to achieve specific rescue of differentiated hepatocytes from methotrexate toxicity. This was accomplished by administration of a conjugate formed by covalent coupling of the methotrexate antagonist, folinic acid (leucovorin), to galact...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Wu GY,Wu CH,Stockert RJ

更新日期：1983-05-01 00:00:00

abstract：:A Raleigh, NC, population of Drosophila melanogaster was sampled for the presence of enzyme null alleles at 25 loci. No nulls were found at any of five X-linked loci. Nulls were recovered at 13 of 20 autosomal loci; the weighted mean frequency for all 20 autosomal loci was estimated to be 0.0025. A consideration of th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Voelker RA,Langley CH,Brown AJ,Ohnishi S,Dickson B,Montgomery E,Smith SC

更新日期：1980-02-01 00:00:00

abstract：:Although sunlight provides the energy necessary for plants to survive and grow, light can also damage reaction centers of photosystem II (PSII) and reduce photochemical efficiency. To prevent damage, plants possess photoprotective mechanisms that dissipate excess excitation. A subset of these mechanisms is collectivel...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Leonelli L,Brooks MD,Niyogi KK

更新日期：2017-08-15 00:00:00

abstract：:Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a strong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organophosphates and carbamates. Here, we rep...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Mutero A,Pralavorio M,Bride JM,Fournier D

更新日期：1994-06-21 00:00:00

abstract：:The water channel aquaporin 1 (AQP1) and certain Rh-family members are permeable to CO(2) and NH(3). Here, we use changes in surface pH (pH(S)) to assess relative CO(2) vs. NH(3) permeability of Xenopus oocytes expressing members of the AQP or Rh family. Exposed to CO(2) or NH(3), AQP1 oocytes exhibit a greater maxima...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Musa-Aziz R,Chen LM,Pelletier MF,Boron WF

更新日期：2009-03-31 00:00:00

abstract：:Previous reports of a relatively air-stable soluble hydrogenase from the photosynthetic anaerobe, Chromatium vinosum, have been substantiated. The properties of this enzyme, as seen in highly purified samples prepared by procedures that permit improved yields, are described. A possible role for flavin mediation is not...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Kakuno T,Kaplan NO,Kamen MD

更新日期：1977-03-01 00:00:00

abstract：:A retinoid was isolated by a multistep procedure from the small intestines of vitamin A-deficient rats given a single dose of retinoic acid. The compound, designated 8II, was pure, as demonstrated by four high-pressure liquid chromatographic procedures. It was positively identified as 5,8-oxyretinoic acid by ultraviol...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Napoli JL,McCormick AM,Schnoes HK,DeLuca HF

更新日期：1978-06-01 00:00:00

abstract：:A longstanding problem in the social, biological, and computational sciences is to determine how groups of distributed individuals can form intelligent collective judgments. Since Galton's discovery of the "wisdom of crowds" [Galton F (1907) Nature 75:450-451], theories of collective intelligence have suggested that t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Becker J,Brackbill D,Centola D

更新日期：2017-06-27 00:00:00

abstract：:Ciliary Neurotrophic Factor (CNTF) was first characterized as a trophic factor for motor neurons in the ciliary ganglion and spinal cord, leading to its evaluation in humans suffering from motor neuron disease. In these trials, CNTF caused unexpected and substantial weight loss, raising concerns that it might produce ...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Lambert PD,Anderson KD,Sleeman MW,Wong V,Tan J,Hijarunguru A,Corcoran TL,Murray JD,Thabet KE,Yancopoulos GD,Wiegand SJ

更新日期：2001-04-10 00:00:00

abstract：:The protooncogene src encodes two proteins, designated pp60c-src+ and pp60c-src.pp60c-src+ is expressed only in neurons, whereas pp60c-src is expressed in neuronal and nonneuronal cells. pp60c-src+ differs from pp60c-src in that it contains an insert of 6 amino acids. To study the evolutionary conservation of the 6-am...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Yang XM,Martinez R,Le Beau J,Wiestler O,Walter G

更新日期：1989-06-01 00:00:00

abstract：:The increasing frequency of antibiotic resistance in hospital-acquired infections is a major public health concern that has both biological and economic causes. Here we develop conceptual mathematical models that couple the economic incentives and population biology of hospital infection control (HIC). We show that th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Smith DL,Levin SA,Laxminarayan R

更新日期：2005-02-22 00:00:00

abstract：:Complement receptors (CRs), expressed notably on myeloid and lymphoid cells, play an essential function in the elimination of complement-opsonized pathogens and apoptotic/necrotic cells. In addition, these receptors are crucial for the cross-talk between the innate and adaptive branches of the immune system. CR3 (also...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Bajic G,Yatime L,Sim RB,Vorup-Jensen T,Andersen GR

更新日期：2013-10-08 00:00:00

abstract：:Previous attempts to express functional DNA cytosine methyltransferase (EC 2.1.1.37) in cells transfected with the available Dnmt cDNAs have met with little or no success. We show that the published Dnmt sequence encodes an amino terminal-truncated protein that is tolerated only at very low levels when stably expresse...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Tucker KL,Talbot D,Lee MA,Leonhardt H,Jaenisch R

更新日期：1996-11-12 00:00:00

abstract：:Topological mechanical metamaterials are artificial structures whose unusual properties are protected very much like their electronic and optical counterparts. Here, we present an experimental and theoretical study of an active metamaterial--composed of coupled gyroscopes on a lattice--that breaks time-reversal symmet...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Nash LM,Kleckner D,Read A,Vitelli V,Turner AM,Irvine WT

更新日期：2015-11-24 00:00:00

abstract：:Depression is a multifactorial illness and genetic factors play a role in its etiology. The understanding of its physiopathology relies on the availability of experimental models potentially mimicking the disease. Here we describe a model built up by selective breeding of mice with strikingly different responses in th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： El Yacoubi M,Bouali S,Popa D,Naudon L,Leroux-Nicollet I,Hamon M,Costentin J,Adrien J,Vaugeois JM

更新日期：2003-05-13 00:00:00

abstract：:We have evaluated two synthetic epothilone analogues lacking the 12,13-epoxide functionality, 12,13-desoxyepothilone B (dEpoB), and 12,13-desoxyepothilone F (dEpoF). The concentrations required for 50% growth inhibition (IC(50)) for a variety of anticancer agents were measured in CCRF-CEM/VBL1000 cells (2,048-fold res...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Chou TC,O'Connor OA,Tong WP,Guan Y,Zhang ZG,Stachel SJ,Lee C,Danishefsky SJ

更新日期：2001-07-03 00:00:00

abstract：:L-type Ca(2+) currents conducted by CaV1.2 channels initiate excitation-contraction coupling in the heart. Their activity is increased by β-adrenergic/cAMP signaling via phosphorylation by PKA in the fight-or-flight response, but the sites of regulation are unknown. We describe the functional role of phosphorylation o...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Fu Y,Westenbroek RE,Scheuer T,Catterall WA

更新日期：2013-11-26 00:00:00

abstract：:Neural crest cell derivatives have been suggested to be involved in thymus development. We established nonlymphoid thymic stromal cell cultures capable of supporting T-cell differentiation. In these nonlymphoid cell cultures, we identified cells with phenotypic and biochemical markers specific for neuronal cells. Neur...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Screpanti I,Meco D,Scarpa S,Morrone S,Frati L,Gulino A,Modesti A

更新日期：1992-04-15 00:00:00

abstract：:The Tap protein mediates the sequence nonspecific nuclear export of cellular mRNAs as well as the sequence-specific export of retroviral mRNAs bearing the constitutive transport element (CTE). Previously, the structures of individual Tap subdomains, including ribonucleoprotein and leucine-rich repeat domains, have bee...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Ho DN,Coburn GA,Kang Y,Cullen BR,Georgiadis MM

更新日期：2002-02-19 00:00:00

abstract：:neurogenin2 (ngn2) encodes a basic helix-loop-helix transcription factor and plays an important role in neurogenesis from migratory neural crest cells. Its role in retinal development is poorly understood. We observed that in the developing chick retina, ngn2 was expressed in a subpopulation of proliferating progenito...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Yan RT,Ma WX,Wang SZ

更新日期：2001-12-18 00:00:00

abstract：:The high-pressure behavior of amorphous selenium has been investigated with time-resolved diamond anvil cell synchrotron x-ray diffraction and computed microtomography techniques. A two-step dynamic crystallization process is observed in which the monoclinic phase crystallized from the amorphous selenium and gradually...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Liu H,Wang L,Xiao X,De Carlo F,Feng J,Mao HK,Hemley RJ

更新日期：2008-09-09 00:00:00

abstract：:The stoichiometry of J chain in pentamer IgM has been determined by measuring the radiolabeled thiols in the constituent chains after complete reduction and alkylation of the polymer. One mole of J was found to be disulfide bonded to 1 mol of pentamer. The linkage of J chain in IgM has been determined by correlating t...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Chapuis RM,Koshland ME

更新日期：1974-03-01 00:00:00

abstract：:p70 S6 kinase (p70(S6k)) is a mitogen-activated protein kinase that plays a central role in the control of mRNA translation. It physiologically phosphorylates the S6 protein of the 40s ribosomal subunit in response to mitogenic stimuli and is a downstream component of the rapamycin-sensitive pathway, which includes th...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Burnett PE,Blackshaw S,Lai MM,Qureshi IA,Burnett AF,Sabatini DM,Snyder SH

更新日期：1998-07-07 00:00:00

abstract：:Bacteria form colonies and secrete extracellular polymeric substances that surround the individual cells. These spatial structures are often associated with collaboration and quorum sensing between the bacteria. Here we investigate the mutual protection provided by spherical growth of a monoclonal colony during exposu...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Eriksen RS,Svenningsen SL,Sneppen K,Mitarai N

更新日期：2018-01-09 00:00:00

abstract：:Rad51 is the primary eukaryotic recombinase responsible for initiating DNA strand exchange during homologous recombination. Although the subject of intense study for over a decade, many molecular details of the reactions promoted by Rad51 and related recombinases remain unknown. Using total internal reflection fluores...

journal_title：Proceedings of the National Academy of Sciences of the United States of America

authors： Granéli A,Yeykal CC,Robertson RB,Greene EC

更新日期：2006-01-31 00:00:00